Synthetic gem composition and method



Patented Aug. 19, 1947 UNlTED STATES PATENT GFFICE.

SYNTHETIC GEM COMPOSITION AND METHOD Serial No. 594,796

9 Claims.

I This invention relates to hard, smooth surfaced synthetic gemcompositions whose surfaces arecapable of taking a high polish, and themethod of making such compositions. More particularly it relates to suchcompositions in which copper oxide and titanium oxide are combined withat least two other color oxides to provide colored compositions such asa black or silver black composition.

A large variety of rocksv and minerals usable for various purposes hasits value enhanced by the relative rarity of the materials. The factorof chance in the locating of whatever supplies of. such materials existand the fact that Where such supplies are located they are not normallyextensive, tend to add to the value of the materials. Other factorsaffecting the appeal of such materials are their durability, theirchemical resistance, their light reflective properties, their pleasingcolor, susceptibility to easy working, their variations in design andstructure, and their capability of taking a high polish on the surfacethereof. In the commercialization of these rocks or minerals any one orany combination of the above factors may be determinative of theirusefulness. Some factors enhance their value as pieces of jewelry,others are more important in capacities such as bearings for delicateinstruments, thread guides or phonograph needles, while luxury uses suchas for cigarette boxes, statuary and clothing accessories may takeadvantage of other characteristics.

Examples of materials of the type just referred to are hematite,obsidian, onyx or sphalerite.

These are commonly used in the preparation of steel gray, black andwalnut brown settings for mens rings, in the preparation of cameo andintaglio designs. These materials are used not only because they aresusceptible of taking a high polish but also because though quite hardthey are not too hard to preclude the cutting of a design into them.Vari-colored onyx is another one of the materials used as indicated. Itis often employed as an expensive furniture accessory.

The disadvantages attendant on the use of the materials above referredto are quite numerous. As already pointed out, the supply is uncertainand even then, considerable variation in that supply is the usual thing.Furthermore it is necessary to cut any design that may be desired intothe material which limits the designs that may be employed and, in somecases, involves considerable expense. This expense is attendant upon anyworkings of such materials for it is work that must be performed byhighly skilled artisans and different artisans are needed for each classof materials and often for each type of operation to be performed onthose materials.

The compositions of this invention are fitting, though economical,replacements for the stones and minerals described above. Mycompositions p'oss'ess characteristics of hardness, strength, durabilityand density comparable to those of the stones and minerals referred to.Nevertheless, they can, if required for jewelry pieces, be

formed with intricate though accurate designs of considerable variety,and the manner of forming is such that the only finishing operation thatis needed is the polishing of the surface. Furthermore, by following themethod of my invention, these compositions can be formed withconsiderable speed and in substantial volume so that a highly economicalproduct results. The color and physical characteristics of this prod=not can also be controlled and duplicated. The product is tougher andmore dense than the usual semi-precious'stones and is as hard or harderthan the run of such stones. Finally, material which is uniformly jetblack or silver black can be produced in accordance with the method ofmy invention and can be duplicated with uniformity; These are among themost difi'icult colors to produce or duplicate.

It is therefore an object of the invention to provide compositions whichwill serve as suitable replacements for semi precious stone materialsheretofore employed found in nature.

It is another object of the invention to provide a method for formingsuch compositions.

Another object of the invention is to provide compositions beinguniformly colored in the color desired and having hard surfaces capableof taking a high polish.

Still other objects of the invention concern compositions and process ofmaking the sam in which the finished form may present suitable designswithout the necessity of expensive -cutting operations.

Further objects of the invention concern the provision of compositionsof high quality which are nevertheless economical to produce and can bereproduced with uniformity.

These and still further objects of the invention will be apparent fromthe ensuing disclosure of the preferred embodiment thereof and method offorming the same.

As an example of the generally preferred and more simple composition ofmy-invention, the

same consists of at least copper oxide, at least 5% titanium oxide withthe balance, or major part, of the mix consisting of two or more of theoxides taken from the group iron oxide, cobalt oxide, nickel oxide andchromium oxide. Such a composition provides for the resultant product tobe of maximum density. In cases, however, where maximum density is notrequired, it is more economical to flux the base oxides with one or moreof the silicates taken from the group calcium silicate, calciummagnesium silicate, the

mineral known as nepheline syenite, which is a sodium aluminum silicate,or feldspar, preferably a potash feldspar. Though these fluxes of coursereduce the density, they may nevertheless be used to the extent of 50%of the total composition without affecting the deep black color whichcan be obtained without them.

In order to develop the description of the method of my invention, letus assume that the composition to be worked with consists of 100 partsof titanium oxide, 100 parts of copper oxide, 800 parts of iron oxideand 800 parts of cobalt oxide. This material must first be prepared andthen be fired. As part of the preparation I carefully select the oxidesto be used and preferably employ those which have been chemicallyprepared. As an example of this, the iron oxide which I prefer to use isthat which is normally employed as a. pigment and is produced by thecalcination of copperas or other sulphate compound.

As the initial step in the preparation, once the properly selectedmaterials in proper quantities have been assembled, I mix them in asuitable mixing device such as a blender, and pass them through adisintegrating machine in order to separate the agglomerates. Thispreliminary preparation having been completed, the first real stage ofpreparation is now in order. This stage involves the calcination of thebatch at a bright red heat, continuing for a sufficient length of timeto assure that every portion of the batch has been subjected to the fullheat for at least an hour. This calcination of the batch is a requisitefor the provision of a final article which will take a suitable polish.

After the completion of the calcination, the batch is ground in a pebblemill in wet slip form up to a fineness that will pass a 400 mesh screen.As an additiontal step to assure its fineness and uniformity, the batchis passed through a silk bolting cloth in order to eliminate any coarseparticles. The remaining product is dried to powder form. The driedpowder is disintegrated and is then ready to be mixed with pressing aidsso that it may be given the proper formation for the final firing andfinishing steps. The batch and treatment of the same just discussed are,as previously pointed out, the pure mixture which I employ when economyis not a factor and where maximum density is required. If, however, amore economical mix is desired and density is not so important, I mayemploy a flux in an amount up to 50% of the total composition. Thesefluxes could, generally speaking, be at least one of the silica bearingtype or, as already pointed out, could be calcium silicate, calciummagnesium silicate, nepheline syenite or a potash feldspar.

To flux the mixture just described or any mixture involving the desirednumber of the oxides, copper oxide, titanium oxide, iron oxide, nickeloxide, cobalt oxide and chromium oxide, they are calcined together,dried and disintegrated as just described. The finely powdered flux isthen added to the calcined mixture of oxides, the body' is blended andis ready to prepare for pressing into shape.

Assuming that the batch, whether including 5 flux or not, has beenprepared to the stage where it is a dried powder, I next prepare it forforming and firing. This calls for mixing the dried powder with pressinaids to hold portions of it in shape when they are formed ready to befired. I use the pressing aids usual in the ceramic industry, such aswax emulsions, solutions of starch, dextrine and the like. Suitableportions of it are then formed into pre-selected shape or withpre-selected designs by pressing them in presses equipped with suitablyshaped dies. The pieces thus shaped are then allowed to stand until theyare dried.

The formed and dried pieces are fired to the maturation temperaturewhich for this particular composition is 2,000 P. An absolute control tothis temperature is not, however, necessary, for one fortunate advantageof this particular composition is that the firing temperature can run upto 2200" F. without destroying the desired properties of the material.Once the firing has been completed and the blank piece has cooled, itssurface can then be finished and polished according to procedure wellknown to lapidaries.

As previously noted, the material of my invention will take a highpolish whether it is of maximum density or is fiuxed to a less densemixture. In order to obtain such a polish, however, the preparation forfiring must be carefully carried out and uniformly followed. Thisassures that the crystalline structure Which develops in the course ofthe firing is such that the body is substantially at Zero porosity andthe grains can be sectioned without fracture. Thus no space can beallowed to develop between the particles in the crystallization process.

While the foregoing description deals specifically with one of thecompositions of my invention, the constituents of the same and themethod followed in forming the same, I have, as already pointed out,determined that a comparable product can be produced though theconstituents and their proportions are varied somewhat. The followingtable shows examples of such variations:

Example mo, 00 0 Any of the batches made in accordance with the aboveexamples may be diluted with any one of the silica bearing fiuxes, aspointed out above in considering the preferred composition. The modifiedcompositions like the preferred one present a uniform solid color.

From the above, it will be readily apparent that I have devised not onebut several compositions which meet the demand for high grade ornamentalmaterial. The supply of them is ample and is not open to the speculativeaspect introduced when any relatively rare material must be discoveredin the earth and then mined. Furthermore my composition may be workedmuch more economically than mined stones, yet the product of myinvention has all the strength, durability, toughness and hardness ofsuch stones or materials. From the variety of constituents I havedisclosed and the variety of proportions of the same, it is obvious thatmy disclosure is merely illustrative and that changes and modificationsmay be made in such embodiments without departing from the spirit orscope of my invention. Accordingly it is to be understood that the scopeof my invention should be construed in accordance with the prior art andthe appended claims and not by reference to the proportions andcombinations which I have employed for purposes of illustration.

I claim:

1. A composition material comprising black copper oxide, white titaniumoxide and at least two of the oxide taken from the group iron oxide,cobalt oxide, nickel oxide and chromium xide, the sum of the copperoxide and titanium oxide being less than the remainder of thecomposition.

2. A composition material comprising minor proportions of black copperoxide and white titanium oxide, and major proportions of at least two ofthe oxides taken from the group iron oxide, cobalt oxide, nickel oxideand. chromium oxide.

3. A composition material comprising minor proportions of black copperoxide and titanium oxide, and the remainder, being at least 75% of thetotal, being comprised of two of the oxides from the group iron oxide,cobalt oxide, nickel oxide and chromium oxide.

4. A composition material comprising at least copper oxide, at least 5%titanium oxide, and the balance consisting of at least two of the oxidestaken from the group iron oxide, cobalt oxide, nickel oxide and chromiumoxide.

5. A composition material comprising black copper oxide, white titaniumoxide, at least two of the oxides from the group iron oxide, cobaltoxide, nickel oxide and chromium oxide, and a flux of at least one ofthe following silicates: calcium silicate, calcium magnesium silicate,nepheline syenite, potash feldspar.

6. A composition material comprising at least 5% copper oxide, at least5% titanium oxide, and the balance consisting in major proportions of atleast two of the oxides taken from the group iron oxide, cobalt oxide,nickel oxide and chromium oxide, and a flux consisting of at least oneof the following silicates: calcium silicate, calcium magnesiumsilicate, nepheline syenite, potash feldspar.

7. The method of forming a, hard composition material which comprisesmixing together black copper oxide and titanium oxide with parts of atleast two of the oxides from the group including iron oxide, cobaltoxide, nickel oxide and chromium oxide in particle size such that theywill pass a 400 mesh screen, calcining the mixture and after calcinationgrinding so that the material will again pass a 400 mesh screen formingit into finished product blanks by mixing with a suitable binder andpressing quantities of it in press equipment and firing the blank soformed to produce a homogeneous mass presenting a hard surface andhaving a uniform color throughout.

8. A method of forming a hard composition material which comprisesmixing together selected size particles of black copper oxide andtitanium oxide in minor proportion, and major proportion of at least twoof the oxides from the group iron oxide, cobalt oxide, nickel oxide andchromium oxide of similarly selected particle size, so that the totalmix is properly and uniformly blended, calcining the entire compositionat a bright red heat for sufiicient time so that every portion has beensubjected to the full heat for at least an hour, grinding the calciningmaterial in wet slip form so that it will again pass a 400 mesh screen,drying the slip, mixing the material with pressing aids and formingblanks from portions of the same by pressing, and then firing suchblanks to a temperature between 2000 F. and 2200 F. to maturate thecomposition, whereby a hard, dense and uniform material simulatingsemi-precious stone is produced.

9. The method of forming a hard composition material which comprisesmixing together black copper oxide and titanium oxide with parts of atleast two of the oxides from the group including iron oxide, cobaltoxide, nickel oxide and chromium oxide in particle size such that theywill pass a 400 mesh screen, calcining the mixture and after calcinationgrinding so that the material will again pass a 400 mesh screen, fiuxingthe calcined mixture by adding thereto a powdered siliceous flux,blending the mixture and flux, forming the composite body into finishedproduct blanks by mixing the body with a suitable binder and pressingquantities of it in press equipment and firing the blank so formed toproduce a homogeneous mass presenting a hard surface and having auniform color throughout.

DANIEL ROSENTHAL.

